import  time
scale=50
print("执行开始".center(scale//2,"-"))
t=time.clock()
for i in range(scale+1):
    a="*"*i
    b="."*i
    c=(i/scale)*100
    t=t-time.clock()
    print("\r{:^3.0f}%[{}->{}]{:.2f}s".format(c,a,b,-t),end='')
    time.sleep(0.1)
    print("\n")